CVE-2021-42554
📋 TL;DR
This vulnerability allows attackers to write predictable data to SMRAM (System Management Mode RAM) through a memory corruption flaw in InsydeH2O firmware's FvbServicesRuntimeDxe component. Successful exploitation could lead to privilege escalation to SMM (System Management Mode), giving attackers high-level system control. Systems using vulnerable InsydeH2O firmware versions are affected.
💻 Affected Systems
- Insyde InsydeH2O firmware
📦 What is this software?
Insydeh2o by Insyde
Insydeh2o by Insyde
Insydeh2o by Insyde
Insydeh2o by Insyde
Insydeh2o by Insyde
Insydeh2o by Insyde
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SMM-level privileges allowing firmware persistence, bypassing OS security controls, and potential hardware-level attacks.
Likely Case
Local privilege escalation from user/admin to SMM level, enabling firmware manipulation and persistent backdoors.
If Mitigated
Limited impact with proper firmware validation and SMM protections, though still a serious firmware-level vulnerability.
🎯 Exploit Status
Requires local access and SMM exploitation knowledge. No public exploits known as of advisory dates.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel 5.0: 05.08.42+, Kernel 5.1: 05.16.42+, Kernel 5.2: 05.26.42+, Kernel 5.3: 05.35.42+, Kernel 5.4: 05.42.51+, Kernel 5.5: 05.50.51+
Vendor Advisory: https://www.insyde.com/security-pledge/SA-2022012
Restart Required: Yes
Instructions:
1. Contact device manufacturer for firmware update. 2. Download appropriate firmware version from manufacturer support site. 3. Follow manufacturer's firmware update procedure. 4. Reboot system after update.
🔧 Temporary Workarounds
SMM protection enforcement
allEnable SMM protection features in BIOS/UEFI settings if available
Restrict physical and administrative access
allLimit who can access systems with vulnerable firmware
🧯 If You Can't Patch
- Isolate affected systems from critical networks and sensitive data
- Implement strict access controls and monitor for suspicious SMM-related activity
🔍 How to Verify
Check if Vulnerable:
Check firmware version in BIOS/UEFI settings or using manufacturer-specific tools. Compare against affected version ranges.Check Version:
Manufacturer-specific (e.g., dmidecode on Linux, wmic bios get smbiosbiosversion on Windows)Verify Fix Applied:
Verify firmware version after update matches patched versions listed in vendor advisory.📡 Detection & Monitoring
Log Indicators:
- Firmware update logs
- SMM access attempts
- BIOS/UEFI modification events
Network Indicators:
- Unusual firmware update traffic
- SMM-related network activity
SIEM Query:
Event logs containing firmware version changes or SMM access patterns🔗 References
- https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf
- https://security.netapp.com/advisory/ntap-20220216-0007/
- https://www.insyde.com/security-pledge
- https://www.insyde.com/security-pledge/SA-2022012
- https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf
- https://security.netapp.com/advisory/ntap-20220216-0007/
- https://www.insyde.com/security-pledge
- https://www.insyde.com/security-pledge/SA-2022012
- https://www.kb.cert.org/vuls/id/796611
